(1) Field of the Invention
This invention relates to automatic door lock circuits for motor vehicles and more specifically to circuits of the type which automatically locks the door locks if a door is opened or becomes ajar and the vehicle is driven at a predetermined speed.
(2) Description of the Prior Art
It is well known in the prior art to provide automatic door locking systems that lock when a predetermined speed is reached. Various electrical control arrangements have been devised for automatically locking vehicle doors.
One arrangement is described in U.S. Pat. No. 3,765,502 dated Oct. 16, 1973 of D. E. Mark. There, an electrical signal of a predetermined duration is generated for automatically locking door lock solenoids when the vehicle reaches a predetermined speed. Such a system appears to provide a relock signal after the door had been previously locked, but no provisions are made for relocking the door locks if the door becomes ajar.
Another vehicle door locking system is described in U.S. Pat. No. 3,722,615 dated Mar. 27, 1973 of Okada et al. There logic and discrete circuits are used to effect automatic locking when the vehicle reaches a certain speed. This system also doesn't consider relocking the door locks after a door becomes ajar while the vehicle is traveling at a predetermined speed.